Fitting nut, fitting, fluid pressure device, and fluid control system, and nut turning tool and fitting nut turning method

ABSTRACT

A fitting nut made of a resin material includes: a hollow, large-diameter tube portion having a female thread formed on its inner peripheral wall; and a small-diameter tube portion that is continuous to the large-diameter tube portion and having a hollow cylindrical shape with a smaller diameter than the large-diameter tube portion. The small-diameter tube portion includes, in the outer peripheral wall thereof, a plurality of engagement grooves that are depressed inwardly in the diameter direction of the small-diameter tube portion and extend along the longitudinal direction that is orthogonal to the diameter direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2019-178168 filed on Sep. 30, 2019, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a fitting nut for connecting a jointbody and a pipe member for sending a fluid, a fitting including thejoint body and the fitting nut, a fluid pressure device including thefitting, and a fluid control system including a plurality of the fluidpressure devices, and to a nut turning tool suitable to turn the fittingnut, and a method for turning the fitting nut.

Description of the Related Art

Apparatuses for manufacturing semiconductors, medical products, etc. orfor processing foods etc., for example, are supplied with high-puritymedical fluids, ultrapure water, etc. from supply sources. A flow ratecontrol valve, which is one type of a fluid pressure device, isinterposed in the piping. A fluid supply pipe is interposed between thesupply source and the flow rate control valve, while a fluid dischargepipe is interposed between the flow rate control valve and themanufacturing or processing apparatus etc. The fluid supply pipe orfluid discharge pipe and the flow rate control valve are connectedtogether through a fitting.

The fitting is formed by engaging a female thread formed on the innerperiphery of a first joint member with a male thread formed on the outerperiphery of a second joint member. As is well known, the male screw isscrewed into the female screw by turning the first joint member or thesecond joint member by means of a suitable tool, like a spanner, wrench,or the like.

Recently, a plurality of flow rate control valves may be arranged in aconcentrated manner in order to make the manufacturing apparatus etc.compact. In such a case, the fittings of the individual flow ratecontrol valves are disposed densely. Under such circumstances, if a toolis turned to attach a fluid supply pipe or a fluid discharge pipe to theflow rate control valve, then the tool will be interfered with byanother fitting. Then, it will be difficult to further turn, in otherwords, to tighten the female nut or male nut. It is also difficult, forthe same reason, to turn the female nut or male nut in the reversedirection to release the engagement therebetween.

Japanese Laid-Open Patent Publication No. 2019-148319 proposes a screwedjoint (fitting) for solving the above problem. The screwed jointincludes a female nut as the first joint member and a male nut as thesecond joint member. The female nut includes a torque-applied portionshaped in a regular hexagon when seen in plan view from a directionperpendicular to its axial direction, and a cylindrical, maximum outerdiameter portion having a female thread formed on its inner periphery.On the other hand, the male nut includes a cylindrical portion having amale thread formed on its outer periphery and a fixed portion shaped ina regular hexagon when seen in plan view from the directionperpendicular to its axial direction. The distance between the opposingsides of the torque-applied portion and that of the fixed portion areset shorter than the outer diameter of the maximum outer diameterportion. A passage pipe in which fluid flows is passed through sleevesindividually accommodated in the female nut and the male nut.

With this configuration, even when fittings are arranged densely, thepitch between adjacent torque-applied portions or between adjacent fixedportions is larger than the pitch between the maximum outer diameterportions. This is because, as mentioned above, the distance between theopposing sides of the torque-applied portion and that of the fixedportion are shorter than the outer diameter of the maximum outerdiameter portion. It is therefore possible to turn the female nut or themale nut by holding the torque-applied portion or the fixed portion witha tool and turning the tool (by applying torque to the torque-appliedportion or the fixed portion). The male thread and the female thread canbe engaged together or released from engagement in either case.

SUMMARY OF THE INVENTION

As can be seen by referring to FIGS. 1, 2, 9 and 10 of JapaneseLaid-Open Patent Publication No. 2019-148319, in the fluid supply systemdescribed in Japanese Laid-Open Patent Publication No. 2019-148319,supply/discharge pipes for supplying and discharging pilot fluids toopen and close the flow rate control valves are provided in areasentirely different from the areas where the fluid supply pipes and fluiddischarge pipes are provided. However, depending on the circumstance, asupply/discharge pipe and a fluid supply pipe, or a supply/dischargepipe and a fluid discharge pipe, may be arranged in a row. In such acase, the supply/discharge pipes are unavoidably arranged densely if theflow rate control valves are arranged in a concentrated manner.Consequently, the tool, which is turned as mentioned above, is likely tobe interfered with by a supply/discharge pipe. It is then difficult tofurther turn, in other words, to tighten the female nut or male nut.

A main object of the present invention is to provide a fitting nut thatcan be tightened even in a small space, for example whensupply/discharge pipes etc. are arranged in rows or when some membersare disposed close to and opposite to the end surfaces thereof, afitting including the same, a fluid pressure device to which a pipemember is connected through the fittings, and a fluid control systemincluding a plurality of the fluid pressure devices, and a nut turningtool suitable to turn and tighten the fitting nut, and a fitting nutturning method using the same.

An embodiment of the present invention provides a fitting nut made of aresin material and having a female thread that is engaged with a malethread formed on an outer peripheral wall of a joint body made of aresin material, the fitting nut including:

a large-diameter tube portion that is hollow and includes the femalethread formed on an inner peripheral wall thereof; and a small-diametertube portion that is continuous to the large-diameter tube portion, hasa hollow cylindrical shape with a smaller diameter than thelarge-diameter tube portion and includes, in an end surface thereof, aninsertion hole in which a pipe member is inserted, wherein thesmall-diameter tube portion includes a plurality of engagement groovesformed in an outer peripheral wall thereof, the plurality of engagementgrooves being depressed inwardly in a diameter direction of thesmall-diameter tube portion and extending along a longitudinal directionthat is orthogonal to the diameter direction.

Another embodiment of the present invention provides a fitting includinga fitting nut configured as described above.

A still another embodiment of the present invention provides a fluidpressure device in which at least one of a fluid supply pipe or a fluiddischarge pipe in which a fluid flows, or a pilot fluid passage pipethrough which a pilot fluid flows, is connected through a fittingconfigured as described above.

A still another embodiment of the present invention provides a fluidcontrol system including a plurality of fluid pressure devices that arearranged in a row and provided with fitting nuts configured as describedabove.

A still another embodiment of the present invention provides a nutturning tool for turning a nut, the nut turning tool including:

an arc-shaped attachment portion shaped like an arc with an opening, thearc-shaped attachment portion being attached to the nut; and

a shaft portion continuous to the arc-shaped attachment portion andextending linearly,

wherein the arc-shaped attachment portion includes, on an inner surfacethereof, one or more claws protruding toward the nut, and

the arc-shaped attachment portion exhibits elasticity in a direction inwhich the opening is closed after being expanded.

A still another embodiment of the present invention provides a fittingnut turning method for turning a fitting nut using a nut turning toolconfigured as described above to thereby engage the fitting nut with ajoint body or to release the engagement with the joint body, the fittingnut turning method including:

causing the fitting nut to enter an opening formed in an arc-shapedattachment portion of the nut turning tool, while expanding the openingwith the fitting nut;

engaging a claw formed on an inner wall of the arc-shaped attachmentportion with an engagement groove formed in an outer peripheral wall ofthe fitting nut, while, when the entry of the fitting nut into theopening ends, closing the opening by elasticity of the arc-shapedattachment portion to attach the arc-shaped attachment portion to thefitting nut; and

applying thereafter torque to the fitting nut through a shaft portion ofthe nut turning tool to turn the fitting nut.

According to the present invention, the small-diameter tube portionhaving a smaller diameter than the large-diameter tube portion is formedcontiguous to the large-diameter tube portion. Since the plurality ofengagement grooves are formed around the small-diameter tube portion, aworker who turns the fitting nut can apply torque to the small-diametertube portion by engaging the claws of the nut turning tool with theengagement grooves and turning the nut turning tool. The fitting nut canthus be turned easily.

Even in an area where the large-diameter tube portions are arrangedadjacent to each other closely, relatively large clearance is formedbetween the small-diameter tube portions having a smaller diameter thanthe large-diameter tube portions. The nut turning tool can be easilyinserted from the clearance so that the nut turning tool is fittedaround the small-diameter tube portion and engaged therewith. It is thuspossible to apply torque to the small-diameter tube portion to turn thefitting nut even in a small space. As a result, it is possible to firmlyscrew the female thread and the male thread together and to release theengagement between the female thread and the male thread.

Furthermore, the arc-shaped attachment portion of the nut tuning toolexhibits such elasticity as to act in the direction in which the openingis closed after being expanded. Accordingly, when attaching thearc-shaped attachment portion to a nut such as a fitting nut, the nutcan be inserted in the arc-shaped attachment portion while the openingis expanded. It is thus possible to easily attach the arc-shapedattachment portion to the nut even in a small space.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following description whentaken in conjunction with the accompanying drawings, in which apreferred embodiment of the present invention is shown by way ofillustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view showing the entirety of a fluidcontrol system;

FIG. 2 is a schematic perspective view of the entirety of a firstair-operated valve of the fluid control system;

FIG. 3 is a schematic plan view of the fluid control system;

FIG. 4 is a schematic longitudinal cross section of the firstair-operated valve;

FIG. 5 is a schematic perspective view of important part in a statewhere a first nut has been removed from a valve body;

FIG. 6 is an enlarged view showing important part of FIG. 4;

FIG. 7 is a schematic perspective view of important part illustrating anut turning tool (first tool), in a state where its arc-shapedattachment portion (small semicircular ring) for applying torque to asmall-diameter tube portion is to be fitted around the small-diametertube portion;

FIG. 8 is a schematic perspective view of important part, in a statewhere a second tool is being used to tighten (retighten or make tighter)a fitting nut of a conventional technique whose outer diameter issubstantially constant along its longitudinal direction;

FIG. 9 is a schematic front view of important part illustrating thestate of FIG. 8;

FIG. 10 is a schematic perspective view of important part, in a statewhere a fitting nut (first nut) of an embodiment of the invention isbeing tightened (retightened or made tighter);

FIG. 11 is a schematic front view of important part showing the state ofFIG. 10;

FIG. 12 is a schematic perspective view of important part, in a statewhere, with the conventional fitting nuts located opposite each other,the second tool for turning is put around a pipe member between fittingnuts;

FIG. 13 is a schematic perspective view of important part, in a statewhere, from the state of FIG. 12, the second tool has been moved andfitted around a fitting nut on one side;

FIG. 14 is a schematic perspective view of important part, in a statewhere, with the fitting nuts (first nuts and second nuts) of theembodiment located opposite each other, a fitting nut (first nut) on oneside is being turned;

FIG. 15 is a schematic longitudinal cross section illustrating the firstair-operated valve, where the first air-operate valve has been broughtfrom the state of FIG. 4 to an opened state by a valve portionseparating from a valve seat;

FIG. 16 is a schematic perspective view illustrating the entirety of afluid control system including positioning and fixing members (endplates) having no tabs;

FIG. 17 is a front view of important part, in a state where, in thestructure shown in FIG. 16, the fitting nuts shown in FIG. 8 are usedand the fitting nut in the center is being turned by the second tool;and

FIG. 18 is a front view of important part, in a state where, in thestructure shown in FIG. 16, the first nuts are used and the first nut inthe center is being turned by the first tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the fluid pressure device and the fluid control system according tothe present invention will be described in detail referring to theaccompanying drawings, in connection with preferred embodimentsillustrating the fittings including the fitting nuts and attached to thefluid pressure device, the nut turning tool for turning the fitting nut,and the fitting nut turning method using the same. It should be notedthat, in the description below, terms like “downward” and “upward”,which particularly correspond to the downward direction and upwarddirection in FIGS. 4 and 15, are used only for convenience in order tofacilitate understanding. Such terms are not intended to specifydirections in practical use of the fluid pressure device. It should alsobe noted that the pipes in which fluid or pilot fluid flows are allshown in cross section.

First, a fluid control system 10 shown in FIG. 1 will be described. Thefluid control system 10 includes first to third air-operated valves 14 ato 14 c that are positioned and fixed on a base 12. The first to thirdair-operated valves 14 a to 14 c are air pressure devices (fluidpressure devices) that operate using compressed air as pilot fluid, andfunction as flow rate control valves for controlling the flow rates offluids such as high-purity medical fluids, ultrapure water, etc.

The first to third air-operated valves 14 a to 14 c are configured asso-called normally-closed valves that are closed when pilot pressuredoes not act. When the first to third air-operated valves 14 a to 14 care in an opened state, the fluids flow from the A1 side to the A2 side.The direction from A1 to A2 will hereinafter be referred to also as“flow direction”. Accordingly, the wording “the upstream side of theflow direction” indicates the A1 side and “the downstream side of theflow direction” indicates the A2 side.

The first air-operated valve 14 a will now be described. As shown in theoverall schematic perspective view of FIG. 2, the first air-operatedvalve 14 a includes an end plate 20 (positioning and fixing member), avalve body 22, a first housing 24, and a second housing 26 in this orderfrom the side of the base 12 (certain member). The first air-operatedvalve 14 a has a vertically oriented, substantially rectangularparallelepiped shape, in which the end plate 20, the valve body 22, thefirst housing 24, and the second housing 26 are connected on the sameaxis line. The end plate 20, the valve body 22, the first housing 24,and the second housing 26 are all made of resin material. Preferredexamples of the resin material include chemical-resistant andheat-resistant fluorine compound resins, such aspolytetrafluoroethylene, polyvinylidene fluoride, perfluoroalkoxyalkane, etc.

As shown in FIG. 3 that is a schematic plan view of the fluid controlsystem 10, one side surface of the end plate 20 of the firstair-operated valve 14 a has a first tab 28 protruding along a B1direction that is perpendicular to the flow direction. The first tab 28is provided integrally with the end plate 20 in a position shifted tothe A2 side. Further, the other side surface on the back of that onesurface has a second tab 30 protruding along a B2 direction that isopposite to the B1 direction. The second tab 30 is provided integrallywith the end plate 20 in a position shifted to the A1 side. That is, thefirst tab 28 and the second tab 30 protrude in the opposite directionsin point-symmetrical positions of the end plate 20. The first tabs 28and the second tabs 30 are thus arranged in a so-called zigzag fashion.

The first tab 28 and the second tab 30 respectively have a firstelongated hole 32 and a second elongated hole 34 as through holesextending along their thickness direction. Threaded portions of mountingscrews 36 are passed respectively through the first elongated hole 32and the second elongated hole 34, and the threaded portions are screwedinto threaded holes formed in the base 12, whereby the firstair-operated valve 14 a is positioned and fixed on the base 12.

A first nut 40 and a second nut 42, being the fitting nuts of theembodiment, are attached respectively to the A1-side end surface andA2-side end surface of the valve body 22, thereby forming a firstfitting portion 44 and a second fitting portion 46 (both are fittings).The first fitting portion 44 and the second fitting portion 46 will bedescribed later.

FIG. 4 is a schematic longitudinal cross section of the firstair-operated valve 14 a, and FIG. 5 is a schematic perspective view ofimportant part illustrating a state where the first nut 40 has beenremoved from the valve body 22. As shown in FIGS. 4 and 5, the valvebody 22 has a first joint body 48 protruding from its A1-side endsurface and a second joint body 50 protruding from its A2-side endsurface. The first joint body 48 extends on the A1 side and the secondjoint body 50 extends on the A2 side. That is, the first joint body 48and the second joint body 50 extend along the flow direction. Needlessto say, the first joint body 48 and the second joint body 50 are formedintegrally with the valve body 22. In other words, the first joint body48 and the second joint body 50 are part of the valve body 22 andtherefore made of resin material.

As shown in FIG. 4, an inlet passage 52, a valve chamber 54, and anoutlet passage 56 are formed in the interior of the valve body 22. Theinlet passage 52 extends from the end of the first joint body 48 on theA1 side to the valve chamber 54, and is opened into the valve chamber54. A valve seat 58 is provided in the vicinity of the opening. On theother hand, the outlet passage 56 extends from the valve chamber 54 tothe end of the second joint body 50 on the A2 side. That is, the inletpassage 52 and the outlet passage 56 communicate with each other throughthe valve chamber 54.

In the interior of the valve body 22, a first tube wall 60 surroundingthe valve seat 58 to form the valve chamber 54, and a second tube wall62 surrounding the first tube wall 60, extend toward the first housing24. A ring-shaped groove 64 is formed between the first tube wall 60 andthe second tube wall 62. The outer edge of a diaphragm 66 is inserted inthe ring-shaped groove 64. A valve portion 68 protrudes toward the valveseat 58, from a radially central area of the lower surface of thediaphragm 66. When the valve portion 68 is seated on the valve seat 58,the communication between the inlet passage 52 and the valve chamber 54is cut off. Further, from the radially central area of the upper surfaceof the diaphragm 66, a substantially cylindrical engaging protrusion 70protrudes toward the first housing 24.

The A1-side end and the A2-side end of the outer peripheral walls of thesecond tube wall 62 integrally connect to the outer walls of the valvebody 22 that form a substantially rectangular shape.

From the lower surface of the first housing 24, which faces the valvebody 22, a ring-shaped protrusion 72 protrudes in a position opposite tothe first tube wall 60. The ring-shaped protrusion 72 is inserted insidethe second tube wall 62 and holds the outer edge of the diaphragm 66together with the first tube wall 60. By this, the diaphragm 66 is heldby the valve body 22 and the first housing 24. On the other hand, fromthe upper surface of the first housing 24 that faces the second housing26, a ring-shaped engagement portion 74 having a larger diameter thanthe ring-shaped protrusion 72 protrudes.

The first housing 24 is a hollow body and its inner chamber is sectionedby a partition 76 into a lower chamber 80 and an upper chamber 82. Thehorizontal cross sections of the lower chamber 80 and the upper chamber82, taken along the flow direction, are substantially perfect circles,and the upper chamber 82 has a larger diameter than the lower chamber80. The lower chamber 80 and the valve chamber 54 are divided by thediaphragm 66. In other words, the diaphragm 66 cuts off thecommunication between the lower chamber 80 and the valve chamber 54. Abreathing port 84 communicating with the lower chamber 80 is formed inthe A2-side end surface of the first housing 24. On the other hand, inthe A1-side end surface of the first housing 24, a first pilot port 86communicating with the upper chamber 82 is formed.

A first guide tube portion 88 is integrally formed with the partition76, the lower and upper ends of the first guide tube portion 88protruding in the lower chamber 80 and the upper chamber 82,respectively. The first guide tube portion 88 is a cylindrical portionhaving a first guide hole 90 extending therethrough along its axialdirection.

A second guide tube portion 92 and a third tube wall 94 protrude intothe second housing 26 from the inner surface of the ceiling wall of thesecond housing 26. A ring-shaped first recess 96 is formed between thesecond guide tube portion 92 and the third tube wall 94. Further, aring-shaped second recess 98 is formed between the third tube wall 94and the substantially rectangular outer walls of the second housing 26.Most part of a return spring 100 is accommodated in the first recess 96.On the other hand, the ring-shaped engagement portion 74 is inserted inthe second recess 98. Further, a second pilot port 102 is formed in theA1-side end surface of the second housing 26. The first recess 96 andthe second pilot port 102 communicate with each other through acommunication passage 104 passing through the third tube wall 94.

The first housing 24 and the second housing 26 accommodate a valve rod110 that is integrally formed with a piston portion 108. The lower endof the return spring 100 rests on the upper end surface of the pistonportion 108, to thereby resiliently bias the valve rod 110 in thedirection toward the valve seat 58 at all times. As will be describedlater, the valve rod 110 is displaced as the piston portion 108 receivespressure (pilot pressure) of the pilot fluid. Some clearance is formedbetween the relatively long side wall of the piston portion 108 and theinner wall of the upper chamber 82, but the clearance between the twowalls is sealed by a ring-shaped seal member 126.

The valve rod 110 includes a first shaft portion 112 protruding from thelower end surface of the piston portion 108, a second shaft portion 114protruding from the upper end surface of the piston portion 108, and athird shaft portion 116 having a smaller diameter, connected to thesecond shaft portion 114 and extending to the ceiling wall of the secondhousing 26. The first shaft portion 112 has an engaging hole 118 that isdepressed toward the piston portion 108. The above-mentioned engagingprotrusion 70 as part of the diaphragm 66 is fitted in the engaging hole118. This fitting allows the diaphragm 66 to be held by the valve rod110 through the engaging protrusion 70.

The first shaft portion 112 is inserted in the first guide hole 90formed in the first guide tube portion 88 that is part of the firsthousing 24. On the other hand, the second shaft portion 114 and thethird shaft portion 116 are inserted in a second guide hole 120 formedin the second guide tube portion 92 that is part of the second housing26. Since the second guide hole 120 is opened in the ceiling wall of thesecond housing 26, a worker or user who operates the fluid controlsystem 10 can visually recognize the third shaft portion 116 in thesecond guide hole 120 when he or she views the first air-operated valve14 a in plan view (see FIG. 3). When the first air-operated valve 14 ais in the closed state, the top surface of the third shaft portion 116and the top surface of the ceiling wall of the second housing 26 aresubstantially flush with each other.

The valve rod 110 is displaced with the first shaft portion 112 beingheld by the first guide tube portion 88 and with the second shaftportion 114 being held by the second guide tube portion 92. In addition,the side wall of the piston portion 108 extends along the innerperipheral wall of the upper chamber 82 in a large area, and theclearance between the two walls is small. It is therefore possible toavoid the situation where the axial direction of the valve rod 110 isinclined with respect to the axial direction of the first air-operatedvalve 14 a. Needless to say, when the valve rod 110 is displaced, thefirst shaft portion 112 is guided by the first guide tube portion 88 andthe second shaft portion 114 is guided by the second guide tube portion92.

As the valve rod 110 is displaced, the engaging protrusion 70 of thediaphragm 66 is pushed or pulled by the first shaft portion 112. Thediaphragm 66 is therefore displaced in the same direction as the valverod 110. With the displacement, the valve portion 68 of the diaphragm 66is seated on or separated from the valve seat 58. That is, the inletpassage 52 and the valve chamber 54 are cut off from each other or madeto communicate with each other, and the first air-operated valve 14 a isbrought into the closed state or the opened state.

Reference numerals 122, 124, 126, 128, 130 shown in FIG. 4 indicatering-shaped seal members. Further, the end plate 20 has screw tighteningholes (not shown) formed in its four corners, and the valve body 22, thefirst housing 24, and the second housing 26 have rod insertion holes(not shown) formed in their four corners. Tie rods (not shown) areinserted from the rod insertion holes of the second housing 26, andthreaded portions of the tie rods are screwed into the screw tighteningholes. The end plate 20, the valve body 22, the first housing 24, andthe second housing 26 are thus fastened together.

Rubber caps 134 (see FIGS. 1 to 3) are press fitted in the rod insertionholes of the second housing 26. By the rubber caps 134, the rodinsertion holes and the screw tightening holes are closed and keptgas-tight or liquid-tight. That is, the rubber caps 134 prevent entry offoreign matter, such as dust, liquid, etc., into the rod insertion holesand the screw tightening holes. Further, since the tie rods made ofmetal are sealed by the rubber caps 134, the tie rods are protected frommoisture and liquid. That is, this effectively prevents corrosion of thetie rods due to adhesion of moisture or liquid. In addition, even ifforeign matter like corrosion powder, metal powder, etc. generates fromthe tie rods, the foreign matter is sealed in the rod insertion holes bythe rubber caps 134. This eliminates the fear of mixing of the foreignmatter into the fluid etc.

As shown in FIG. 1, a first supply/discharge pipe 144 and a secondsupply/discharge pipe 146 (both are pilot fluid passage pipes) areconnected to the first pilot port 86 and the second pilot port 102through a first joint 140 and a second joint 142, respectively.Specifically, the first pilot port 86 and the second pilot port 102 eachhave a female thread formed on the inner peripheral wall thereof, andthe first joint 140 and the second joint 142 each have a male threadformed on the outer peripheral wall thereof. The male thread is engagedwith the female thread, whereby the first supply/discharge pipe 144 andthe second supply/discharge pipe 146 are held by the first housing 24and the second housing 26 through the first joint 140 and the secondjoint 142, respectively.

When the first to third air-operated valves 14 a to 14 c are configuredas normally-closed valves as described above, it is not essential toattach the second supply/discharge pipes 146 to the second pilot ports102. For example, the second pilot ports 102 may be closed by plugmembers.

Next, the first fitting portion 44 and the second fitting portion 46provided in the valve body 22 will be described.

As shown in FIG. 5, and FIG. 6 which is an enlarged view of importantpart in FIG. 4, the first fitting portion 44 includes the first jointbody 48 protruding from the A1-side end surface of the valve body 22,and the first nut 40, where the first joint body 48 and the first nut 40hold a fluid supply pipe 150 (pipe member) therebetween. Needless tosay, the interior of the fluid supply pipe 150 communicates with theinlet passage 52 in the first joint body 48.

The first joint body 48 includes a cylindrical proximal portion 152having a relatively large diameter and integrally connected to the valvebody 22. A male thread 154 is formed on the outer peripheral wall of theproximal portion 152.

The first joint body 48 further includes a cylindrical extended shaftportion 156 having a relatively small diameter and protruding to the A1side from the proximal portion 152. A tapered surface 158 whose diametergradually expands from the A1 side toward the A2 side is formed at theend of the extended shaft portion 156.

On the outer peripheral surface of the extended shaft portion 156, aplurality of ring-shaped protrusions 164 are formed in an area on the A2side of the tapered surface 158, the ring-shaped protrusions 164abutting on the inner wall surface of a diameter-increased portion 150 aof the fluid supply pipe 150. The plurality of ring-shaped protrusions164 each have a top having a substantially triangular cross section, andare arranged at certain intervals along the axial direction of theextended shaft portion 156. The ring-shaped protrusions 164 havesubstantially the same height. FIGS. 5 and 6 show an example in whichfive ring-shaped protrusions 164 are provided, but the number of thering-shaped protrusions 164 is not particularly limited to this. Only asingle ring-shaped protrusion 164 may be provided, for example.

On the other hand, the first nut 40 includes a large-diameter tubeportion 170 having a relatively large diameter, and a small-diametertube portion 172 that is contiguous to the large-diameter tube portion170 and that protrudes to the A1 side. Needless to say, thesmall-diameter tube portion 172 has a smaller diameter than thelarge-diameter tube portion 170. The large-diameter tube portion 170 andthe small-diameter tube portion 172 are both formed as hollow tubes.Accordingly, the large-diameter tube portion 170 has a first inner hole174 therein and the small-diameter tube portion 172 has a second innerhole 176 therein. The inner diameter of the first inner hole 174 is setlarger than that of the second inner hole 176.

Then, the inner peripheral wall forming the first inner hole 174 of thelarge-diameter portion 170 has formed thereon a female thread 178 thatengages with the male thread 154 of the first joint body 48. The outerperipheral wall of the large-diameter tube portion 170 has formedthereon a plurality of engagement protrusions 180 protruding outward inthe diameter direction of the large-diameter tube portion 170 (see FIGS.1 to 3). Accordingly, the maximum outer diameter portion of the firstnut 40, where its outer diameter defined as the distance from the centerto the outer circumference is maximum, is the area where each of theengagement protrusions 180 is formed. Each engagement protrusion 180extends along a direction orthogonal to the diameter direction, i.e.,along the longitudinal direction (flow direction) of the large-diametertube portion 170. In this case, six engagement protrusions 180 areprovided and spaced apart from each other at substantially equalintervals.

An insertion hole 182 having a circular cross section is formed in theA1-side end surface (end surface) of the small-diameter tube portion172, and the fluid supply pipe 150 is inserted in the insertion hole182. Further, a ring-shaped pressing portion 184, which forms an acuteangle in cross section, is formed on the inner peripheral wall of thesmall-diameter tube portion 172. When the first nut 40 is tightened onthe first joint body 48, the ring-shaped pressing portion 184 pressesthe inclined outer peripheral surface of the fluid supply pipe 150against the tapered surface 158.

The second inner hole 176 has a larger diameter than the insertion hole182. The inner peripheral wall forming the second inner hole 176 isspaced apart at a certain interval from the ring-shaped protrusions 164on the extended shaft portion 156 of the first joint body 48. Thedistance between the tops of the ring-shaped protrusions 164 and theinner peripheral wall is smaller than the thickness of thediameter-increased portion 150 a of the fluid supply pipe 150 at thetime of the formation of the diameter-increased portion 150 a.

On the outer peripheral wall of the small-diameter tube portion 172, aplurality of ridges protrude outward in the diameter direction of thesmall-diameter tube portion 172. The number of the ridges is larger thanthe number of the engagement protrusions 180 on the outer peripheralwall of the large-diameter tube portion 170. Each ridge extends alongthe longitudinal direction (flow direction) that is orthogonal to thediameter direction of the small-diameter tube portion 172. Accordingly,engagement grooves 186, which are depressed inwardly in the diameterdirection of the small-diameter tube portion 172 and extend along thelongitudinal direction orthogonal to the diameter direction, are formedbetween adjacent ridges. The ridges and the engagement grooves 186alternate along the circumferential direction of the small-diameter tubeportion 172, so that the outer peripheral wall of the small-diametertube portion 172 is formed like so-called straight teeth.

The first nut 40 constructed as described above is made of a resinmaterial like the valve body 22 (joint body). In the same way, the fluidsupply pipe 150 is also made of a resin material. Preferred examples ofthe resin materials include fluorine compound resins listed earlier.

The second fitting portion 46 disposed in the A2-side end surface of thevalve body 22 includes the second joint body 50, the second nut 42, anda fluid discharge pipe 188 that are configured in the same mannerrespectively as the first joint body 48, the first nut 40, and the fluidsupply pipe 150. The second fitting portion 46 will therefore be notdescribed in detail. Concerning the second joint body 50 and the secondnut 42, “A1” in the description of the first joint body 48 and the firstnut 40 is replaced by “A2”. The diameter-increased portion of the fluiddischarge pipe 188 is labeled with reference numeral 188 a (see FIG. 6).

The remaining second and third air-operated valves 14 b and 14 c areconstructed in the same manner as the first air-operated valve 14 a.Accordingly, the same constituent components are labeled with the samereference numerals and will not be described in detail.

FIG. 7 shows a first tool 200, which is a nut turning tool according tothe embodiment, and applies torque to the small-diameter tube portion172 to turn the first nut 40 (or the second nut 42). The first tool 200includes a small handle 202 as a shaft, and a small semicircular ring204 (arc-shaped attachment portion) which is formed of an arc-shaped,thin, curved plate and has a substantially semicircular form. The smallhandle 202 has larger rigidity than the small semicircular ring 204.

The small semicircular ring 204 has a shape such that a ring body is cutinto a substantially semicircular shape, i.e., an arc-like shape. Anopening 205 is therefore formed in the small semicircular ring 204.Further, the small semicircular ring 204, formed of a thin curved plate,has superior elasticity. That is, when an external force acts on theopening 205 and the opening 205 is expanded, the opening 205 easilycloses when the external force disappears. That is, the smallsemicircular ring 204 returns to its original shape.

Further, the inner wall of the small semicircular ring 204 has formedthereon three engagement claws 206 (claws) protruding inwardly in thediameter direction, i.e., toward the first nut 40 (or the second nut42). The inner diameter of the small semicircular ring 204 substantiallymatches the outer diameter of the small-diameter tube portion 172 of thefirst nut 40 and the second nut 42. The pitch or phase differencebetween adjacent engagement claws 206 is substantially equal to thepitch or phase difference between adjacent engagement grooves 186. Thethree engagement claws 206 can thus engage with three engagement grooves186.

FIG. 7 shows an example in which three engagement claws 206 areprovided, but the number of the engagement claws 206 is not particularlylimited to this, so long as it is one or more. That is, two or lessengagement claws 206, or four or more engagement claws 206 may beprovided.

FIG. 8 shows a second tool 210 that can apply torque to thelarge-diameter tube portion 170. The second tool 210 includes a largehandle 212 that is thicker and longer than the small handle 202, and alarge semicircular ring 214 whose inner diameter is larger than that ofthe small semicircular ring 204 and that is somewhat longer than thesemicircle. The large semicircular ring 214 has an opening 215, andincludes five engagement recesses 216 formed in its inner wall anddepressed outward in its diameter direction. The inner diameter of thelarge semicircular ring 214 substantially matches the outer diameter ofthe large-diameter tube portions 170 of the first nut 40 and the secondnut 42. The pitch or phase difference between adjacent engagementrecesses 216 is substantially equal to the pitch or phase differencebetween adjacent engagement protrusions 180. Accordingly, the fiveengagement recesses 216 can engage with five engagement protrusions 180.

While FIG. 8 shows an example in which the number of the engagementprotrusions 180 is six (the phase difference between the engagementprotrusions 180 is about 60°) and the number of the engagement recesses216 is five, the numbers of the engagement protrusions 180 and theengagement recesses 216 are not particularly limited to this example.For instance, even if six engagement protrusions 180 are provided as inthis example, four or less engagement recesses 216 may be provided.Further, five or less, or six or more engagement protrusions 180 may beprovided, with four or less, or six or more engagement recesses 216.

The first tool 200 and the second tool 210 are both made of resinmaterial. Examples of the resin material include fluorine compoundresins, such as polytetrafluoroethylene, polyvinylidene fluoride,perfluoroalkoxy alkane, etc., but may be other resin material. Specificexamples of other resin material include polypropylene, polyethylene,etc.

According to the embodiment, the first nut 40 and the second nut 42(fitting nuts), the first fitting portion 44 and the second fittingportion 46, the first to third air-operated valves 14 a to 14 c (fluidpressure devices), the fluid control system 10 including the same, andthe first tool 200, are constructed basically as described so far. Next,their functions and effects will be described in connection with amethod for turning the fitting nuts (the first nut 40 and the second nut42) that is performed in the process of assembling the fluid controlsystem 10.

In order to fabricate the fluid control system 10, first, the first tothird air-operated valves 14 a to 14 c are positioned and fixed on thebase 12. For this purpose, the threaded portions of the mounting screws36 are inserted respectively in the first elongated holes 32 of thefirst tabs 28 and the second elongated holes 34 of the second tabs 30 ofthe first to third air-operated valves 14 a to 14 c, and the threadedportions are temporarily screwed respectively into the threaded holesformed in the base 12. At this stage, the first to third air-operatedvalves 14 a to 14 c can be displaced along the longitudinal direction ofthe first elongated holes 32 and the second elongated holes 34. That is,the positions of the first to third air-operated valves 14 a to 14 c canbe adjusted. After that, the mounting screws 36 are retightened (madetighter).

Since the first tabs 28 and the second tabs 30 are arranged in a zigzagfashion (see FIG. 3), the second tab 30 of the first air-operated valve14 a and the first tab 28 of the second air-operated valve 14 b, forexample, are arranged in a row on the upstream side (A1 side) and thedownstream side (A2 side) of the flow direction. That is, the second tab30 of the first air-operated valve 14 a is not arranged in a row alongthe B1 direction or B2 direction with the first tab 28 or the second tab30 of the second air-operated valve 14 b. Accordingly, it is possible toset the distance between the valve bodies 22 of the first and secondair-operated valves 14 a and 14 b to be substantially equal to theprotruding length of the second tab 30 of the first air-operated valve14 a in the B2 direction (or the protruding length of the first tab 28of the second air-operated valve 14 b in the B1 direction).

Consequently, the first air-operated valve 14 a and the secondair-operated valve 14 b can be located most closely. The same applies tothe second air-operated valve 14 b and the third air-operated valve 14c. The fluid control system 10 can be made compact for this reason.

In FIG. 3, the side of the first to third air-operated valves 14 a to 14c on which the first pilot ports 86 and the second pilot ports 102 arelocated is the fluid inlet side, and the other side is the fluid outletside, but this is merely an example. A configuration may be adopted inwhich, in at least one of the first to third air-operated valves 14 a to14 c, the side on which the first pilot port 86 and the second pilotport 102 are located is the fluid outlet side and the other side is thefluid inlet side.

Next, the first supply/discharge pipe 144 is connected into the firstpilot port 86 through the first joint 140, and the secondsupply/discharge pipe 146 is connected into the second pilot port 102through the second joint 142. The first supply/discharge pipe 144 andthe second supply/discharge pipe 146 may be connected respectively intothe first pilot port 86 and the second pilot port 102 before positioningand fixing the first to third air-operated valves 14 a to 14 c on thebase 12.

Next, the first fitting portion 44 is assembled. Specifically, first,the end of the fluid supply pipe 150 is inserted into the insertion hole182 of the first nut 40, and the end of the fluid supply pipe 150 ispulled by a given length to the large-diameter tube portion 170 side.Then, the first joint body 48 is inserted into the hollow interior ofthe end.

The extended shaft portion 156 of the first joint body 48 is insertedinto the large-diameter tube portion 170 of the first nut 40, and thefemale thread 178 of the first nut 40 is screwed along the male thread154 of the first joint body 48. That is, the first nut 40 is tightened.The first nut 40 may be first manually tightened by the worker and thenretightened after that, for example.

As the first nut 40 is tightened, the diameter of the fluid supply pipe150 is expanded gradually from the end along the tapered surface 158 ofthe extended shaft portion 156. Also, the inner peripheral wall of thesmall-diameter tube portion 172 of the first nut 40 and the extendedshaft portion 156 of the first joint body 48 gradually overlap along theaxial direction. As a result, the plurality of ring-shaped protrusions164 on the extended shaft portion 156 gradually face the innerperipheral wall forming the second inner hole 176 of the small-diametertube portion 172, starting from the side close to the tapered surface158. The inner peripheral wall facing the ring-shaped protrusions 164presses the outer wall surface of the expanded fluid supply pipe 150against the ring-shaped protrusions 164.

That is, the fluid supply pipe 150 is first expanded by the extendedshaft portion 156 and then deformed while being squeezed sequentiallyfrom the side close to the tapered surface 158. In this way, the innerperipheral wall of the diameter-increased portion 150 a is compressed inthe areas thereof in contact with the ring-shaped protrusions 164, whilebeing swelled inwardly in the diameter direction on both sides thereofand entering the spaces between adjacent ring-shaped protrusions 164.

The diameter-increased portion 150 a of the fluid supply pipe 150 isformed in this way, and the diameter-increased portion 150 a is thusheld between the plurality of ring-shaped protrusions 164 of theextended shaft portion 156 and the inner peripheral wall of thesmall-diameter tube portion 172 of the first nut 40. That is, the innerperipheral wall of the diameter-increased portion 150 a comes in closecontact with the plurality of ring-shaped protrusions 164. A seal isthus provided between the ends of the ring-shaped protrusions 164 andthe inner wall surface of the diameter-increased portion 150 a.

Then, as the first nut 40 is further screwed by manual tightening orretightening, the fluid supply pipe 150 is pinched and pressed betweenthe tapered surface 158 of the extended shaft portion 156 and thering-shaped pressing portion 184 of the first nut 40. As a result, thetapered surface 158 comes in close contact with the inclined inner wallsurface of the fluid supply pipe 150 that is pressed by the innerperipheral wall of the small-diameter tube portion 172. A seal is thusprovided also between the tapered surface 158 and the inclined innerwall surface of the fluid supply pipe 150.

Now, FIGS. 8 and 9 show fitting nuts 230 according to a conventionaltechnique, one of which is being retightened. In order to facilitatevisual recognition and understanding, FIG. 8 omits the valve bodies 22,first housings 24, etc., and the engagement protrusions 180 are labeledwith the same reference numeral as the engagement protrusions 180 of thefirst nut 40. Also, the outer diameter of the fitting nuts 230 is thesame as the outer diameter of the large-diameter tube portion 170 of thefirst nut 40 and substantially constant along the longitudinal directionof the fitting nut 230.

As explained earlier, the first to third air-operated valves 14 a to 14c are arranged in a row. Accordingly, the fitting nuts 230 of the firstto third air-operated valves 14 a to 14 c are arranged in a row from theB1 side to the B2 side.

FIGS. 8 and 9 show an example in which the fitting nut 230 of the secondair-operated valve 14 b is retightened by the second tool 210. In thiscase, as can be seen also referring to FIG. 17, engaging the engagementrecesses 216 of the second tool 210 with the engagement protrusions 180and turning the fitting nut 230 requires that a pitch P1 between theadjacent fitting nuts 230 be set not less than the sum of the tool widthand the outer diameter of the maximum outer diameter portion of thefitting nut 230 (the distance from the center of the fitting nut 230 tothe outer circumferential surfaces of the engagement protrusions 180).This is because, if the pitch P1 is less than the sum, the fitting nuts230 interfere with the large semicircular ring 214 as the second tool210 is moved along the longitudinal direction of the fitting nuts 230.

Hence, the first air-operated valve 14 a and the second air-operatedvalve 14 b, and the second air-operated valve 14 b and the thirdair-operated valve 14 c, cannot be located so close that the pitch P1becomes less than the sum of the outer diameter of the maximum outerdiameter portion of the fitting nut 230 and the tool width. That is, inthis case, it is difficult to locate the first to third air-operatedvalves 14 a to 14 c most closely as explained earlier.

Furthermore, as shown in FIG. 9, when the fitting nut 230 is turned, thefirst joint 140 and the first supply/discharge pipe 144 interfere withthe large handle 212 of the second tool 210 while a turning angle Θ1 isrelatively small. In this case, the large semicircular ring 214 is onceremoved from the fitting nut 230, the large handle 212 is returned tothe position before being turned, and the engagement recesses 216 isengaged with the engagement protrusions 180 again to turn the fittingnut 230 again. However, the retightening work will be troublesome ifthis work has to be repeated many times.

Furthermore, if the turning angle Θ1 is less than the phase differencebetween adjacent engagement protrusions 180 (60° in the example in whichthe six engagement protrusions 180 are provided), then the fitting nut230 of the first air-operated valve 14 a may interfere with the largehandle 212 when engaging the engagement recesses 216 with the engagementprotrusions 180 again. In this case, engaging the engagement recesses216 with the engagement protrusions 180 again itself is difficult.

In contrast, in the embodiment, as shown in FIGS. 10 and 11, since thesmall-diameter tube portions 172 are smaller in diameter than thelarge-diameter tube portions 170, relatively large clearance is formedbetween adjacent small-diameter tube portions 172 even when thelarge-diameter tube portions 170 of the first nuts 40 are located mostclosely. When the worker retightens the first nut 40 of the secondair-operated valve 14 b, the worker inserts the small semicircular ring204 of the first tool 200 into the clearance and then causes thesmall-diameter tube portion 172 to enter the opening 205 of the smallsemicircular ring 204. Since the small semicircular ring 204 hassuperior elasticity, the opening 205 of the small semicircular ring 204is easily expanded. It is thus easy to cause the small-diameter tubeportion 172 to enter the opening 205.

At substantially the same time as the small-diameter tube portion 172enters the opening 205, the expanded opening 205 closes due to theelasticity of the small semicircular ring 204. At substantially the sametime or before that, the three engagement claws 206 formed on the innerwall of the small semicircular ring 204 are engaged respectively withthree of the engagement grooves 186. The first tool 200 is thus attachedto (fitted around) the small-diameter tube portion 172 without comingoff from the small-diameter tube portion 172. In this state, the workerturns the small handle 202 to apply torque to the small-diameter tubeportion 172, to thereby integrally turn the small-diameter tube portion172 and the large-diameter tube portion 170 that is continuous to thesmall-diameter tube portion 172. Since the rigidity of the small handle202 is larger than that of the small semicircular ring 204, the torqueis efficiently transmitted from the small handle 202 to thesmall-diameter tube portion 172.

In this way, according to the embodiment in which the first nut 40 hasthe small-diameter tube portion 172, the first nut 40 can be turned evenwhen the large-diameter tube portions 170 are located most closely. Thatis, depending on the circumstances, particularly as shown in FIGS. 16and 18, a pitch P2 between adjacent first nuts 40 can be setsubstantially equal to the outer diameter of the maximum outer diameterportion of the first nut 40 (the distance from the center of thelarge-diameter tube portion 170 to the outer surfaces of the engagementprotrusions 180). Consequently, the first to third air-operated valves14 a to 14 c can be arranged in a row most closely as has been explainedabove.

Furthermore, as shown in FIG. 11, because the outer diameter of thesmall-diameter tube portion 172 is smaller than that of thelarge-diameter tube portion 170, the turning angle Θ2, from the positionat which turning of the small-diameter tube portion 172 of the first nut40 is started to the position at which the first joint 140 and the firstsupply/discharge pipe 144 interfere with the small handle 202 of thefirst tool 200, is larger than the turning angle Θ1. Thus, the first nut40 can be turned through a larger angle by applying torque to thesmall-diameter tube portion 172 one time. When the first joint 140 andthe first supply/discharge pipe 144 interfere with the small handle 202,the small semicircular ring 204 is once removed from the small-diametertube portion 172, the small handle 202 is returned to the positionbefore being turned, and the engagement claws 206 are engaged with theengagement grooves 186 again, to turn the first nut 40 again. Thus,because the turning angle Θ2 in one turning of the first nut 40 can bemade larger, the first nut 40 can be tightened by turning it a reducednumber of times.

Furthermore, because the pitch or phase difference between adjacentengagement grooves 186 is smaller, it is possible to effectively avoidthe situation where the first nut 40 of the first air-operated valve 14a interferes with the small handle 202 during re-engagement of theengagement claws 206 with the engagement grooves 186. The engagementclaws 206 can thus be re-engaged with the engagement grooves 186 easily.For these reasons, the work of retightening can be easily achieved evenif the turning angle Θ2 is small.

The second fitting portion 46 can be assembled by tightening the secondnut 42 around the second joint body 50 in the same manner. Since thefirst pilot port 86 and the second pilot port 102 are not provided onthe side of the second fitting portion 46 (on the A2 side), there is nofear that the first tool 200 or the second tool 210 is interfered withby the first joint 140, the first supply/discharge pipe 144, etc.,whichever of the first tool 200 and the second tool 210 is used. In sucha case, the second nut 42 may be turned by using the second tool 210.

Specifically, the five engagement recesses 216 formed in the inner wallof the large semicircular ring 214 of the second tool 210 are engagedwith five of the engagement protrusions 180 formed on the outerperipheral wall of the large-diameter tube portion 170 of the second nut42 in the same manner as shown in FIG. 8. Torque is then applied to thelarge-diameter tube portion 170 through the large handle 212. Thelarge-diameter tube portion 170 and the small-diameter tube portion 172that is continuous to the large-diameter tube portion 170 are thusturned integrally.

In this way, because of the formation of the engagement protrusions 180on the outer peripheral walls of the large-diameter tube portions 170 ofthe first nut 40 and the second nut 42, the first nut 40 and the secondnut 42 can not only be turned through the application of torque to thesmall-diameter tube portion 172 by means of the first tool 200, but canalso be turned through the application of torque to the large-diametertube portion 170 by means of the second tool 210. In the latter case,larger torque can be applied compared to when the small-diameter tubeportion 172 is turned. This provides the advantage that the retighteningwork of the first nuts 40 and the second nuts 42 can be achieved easilyin situations where the pipe members or the like are not provideddensely and the second tool 210 can be easily turned.

That is, the formation of the engagement grooves 186 around thesmall-diameter tube portion 172 and the engagement protrusions 180around the large-diameter tube portion 170 enables selective use of thefirst tool 200 and the second tool 210. Hence, when supply/dischargepipes etc. interfere with the second tool 210, then the first tool 200can be used to reliably turn the small-diameter tube portion 172 even ina small space, while the second tool 210 can be used to apply largertorque to the large-diameter tube portion 170 when there is no fear thatsupply/discharge pipes etc. interfere with the second tool 210.

Incidentally, some fluid control device may be disposed on the upstreamside (or the downstream side) of the first to third air-operated valves14 a to 14 c. As shown in FIG. 12, according to conventional techniques,if the fluid control device is located close to the first to thirdair-operated valves 14 a to 14 c along the flow direction, then thefitting nuts 230 of the fluid control device are positioned opposite tothe fitting nuts 230 of the first to third air-operated valves 14 a to14 c. Since the second tool 210 is thick and has a large tool width, itselasticity (flexibility) is poor. The opening of the large semicircularring 214 is therefore hardly expandable. Hence, in this state, it isdifficult to fit the large semicircular ring 214 directly around thefitting nut 230 of the second air-operated valve 14 b, for example.

Accordingly, when retightening the fitting nut 230 of the secondair-operated valve 14 b, first (see FIG. 12), the large semicircularring 214 is put around the fluid supply pipe 150 that is exposed betweenthe fitting nut 230 of the fluid control device and the opposite fittingnut 230 of the second air-operated valve 14 b. Subsequently, as shown inFIG. 13, the second tool 210 has to be moved to the fitting nut 230 (tothe A2 side) of the second air-operated valve 14 b. The engagementrecesses 216 of the second tool 210 thus engage with the engagementprotrusions 180 of the fitting nut 230.

In contrast, as shown in FIG. 14, when the fluid control device includesthe second nuts 42 and the first to third air-operated valves 14 a to 14c include the first nuts 40, and the fluid control device and the firstto third air-operated valves 14 a to 14 c are located close to eachother along the flow direction, then the small-diameter tube portions172 of the second nuts 42 and the small-diameter tube portions 172 ofthe first nuts 40 face each other. Since the first tool 200 is thin andhas a smaller tool width, its elasticity (flexibility) is relativelylarge. Accordingly, the opening 205 of the small semicircular ring 204easily expands when fitting the small semicircular ring 204 around thesmall-diameter tube portion 172. It is therefore easy to cause thesmall-diameter tube portion 172 to enter the opening 205.

Furthermore, after the small semicircular ring 204 has been fittedaround the small-diameter tube portion 172, the opening 205 closes dueto its elasticity. Also, the engagement claws 206 engage with theengagement grooves 186. The first tool 200 is thus attached to thesmall-diameter tube portion 172. It is thus possible to fit the smallsemicircular ring 204 directly around the small-diameter tube portion172 of the first nut 40 of the second air-operated valve 14 b and thento turn the first nut 40 by applying torque to the small-diameter tubeportion 172.

It is therefore not necessary to expose the fluid supply pipe 150between the second nut 42 attached to the fluid control device and theopposite first nut 40 of the second air-operated valve 14 b. Dependingon the circumstances, the downstream end surfaces of the second nuts 42and the upstream end surfaces of the first nuts 40 can be abuttedagainst each other. This allows the fluid control device and the firstto third air-operated valves 14 a to 14 c to be located closer to eachother, which enables the fluid control system 10 to be made furthercompact, or in other words to be more integrated.

The first to third air-operated valves 14 a to 14 c operate as followsto control the flow rates of fluids.

When bringing the first air-operated valve 14 a (or the secondair-operated valve 14 b or the third air-operated valve 14 c) into theopened state to cause high-purity medical fluid or ultrapure water toflow, pilot air is supplied from the first supply/discharge pipe 144into the upper chamber 82 through the first pilot port 86. Thisincreases the internal pressure in the upper chamber 82, and the pistonportion 108 of the valve rod 110 is pressed by the pilot air from itslower surface. As a result, as shown in FIG. 15, the valve rod 110 isdisplaced to the second housing 26 side (i.e., upward in FIGS. 4 and 15)by the amount corresponding to the pilot pressure of the pilot air. Atthis time, the first shaft portion 112 and the second shaft portion 114forming the valve rod 110 and protruding from the piston portion 108 areguided by the inner peripheral walls of the first guide hole 90 and thesecond guide hole 120. Further, the outer peripheral wall of the pistonportion 108 slides along the inner peripheral wall of the upper chamber82. Further, the return spring 100 is pressed by the piston portion 108and compressed.

As the valve rod 110 is displaced upward, the diaphragm 66, whoseengaging protrusion 70 is fitted in the engaging hole 118 of the firstshaft portion 112, is displaced in the same direction as the valve rod110 (i.e., upward). The valve portion 68 of the diaphragm 66 thusseparates away from the valve seat 58. As the diaphragm 66 is displacedupward, the internal volume of the lower chamber 80 decreases and so theair in the lower chamber 80 is discharged from the breathing port 84.

As the valve portion 68 separates away from the valve seat 58, the inletpassage 52 and the valve chamber 54 communicate with each other, and theinlet passage 52 and the outlet passage 56 also communicate with eachother through the valve chamber 54. Then, the fluid that has reached theinlet passage 52 through the fluid supply pipe 150 is introduced intothe valve chamber 54 and flows into the fluid discharge pipe 188 fromthe valve chamber 54 through the outlet passage 56. The high-puritymedical fluid or ultrapure water is thus supplied to the manufacturingapparatus, processing apparatus, or the like.

When the first to third air-operated valves 14 a to 14 c are in theopened state, the upper end of the third shaft portion 116 is exposedfrom the second guide hole 120. The worker or user visually recognizesthe exposed third shaft portion 116 to know that the first to thirdair-operated valves 14 a to 14 c are in the opened state.

When stopping the flow of the fluid like high-purity medical fluid,ultrapure water, etc., the valve portion 68 is seated on the valve seat58. That is, the supply of pilot air from the first supply/dischargepipe 144 is stopped. Further, the pilot air in the upper chamber 82 isdischarged through the first pilot port 86. The discharge reduces theinternal pressure in the upper chamber 82, and then the resilient forceof the return spring 100 exceeds the internal pressure in the upperchamber 82. As a result, the return spring 100 stretches to resilientlybias the piston portion 108 toward the first housing 24. The valve rod110 including the piston portion 108 is thus displaced downward toreturn to the original position.

This displacement increases the internal volume of the lower chamber 80,causing the air to be introduced into the lower chamber 80 through thebreathing port 84. Alternatively, the second pilot port 102 may beconfigured to function as a breathing port. In this case, it is notparticularly necessary to attach the second supply/discharge pipe 146 tothe second pilot port 102. Needless to say, the first shaft portion 112and the second shaft portion 114 are guided by the inner peripheralwalls of the first guide hole 90 and the second guide hole 120 also whenthe valve rod 110 is displaced downward.

As the valve rod 110 is returned to the original position (is displaceddownward), the diaphragm 66 is displaced downward integrally with thevalve rod 110 and the valve portion 68 thereof is seated on the valveseat 58. This cuts off the communication between the inlet passage 52and the outlet passage 56 through the valve chamber 54. That is, thefluid in the inlet passage 52 is prevented from flowing downstream pastthe valve chamber 54.

When the first to third air-operated valves 14 a to 14 c are broughtinto the closed state, the upper end of the third shaft portion 116returns into the second guide hole 120. The worker or user visuallyrecognizes that the top surface of the third shaft portion 116 hasbecome substantially flush with the top surface of the ceiling wall ofthe second housing 26, to know that the first to third air-operatedvalves 14 a to 14 c have returned to the closed state.

The present invention is not particularly limited to the embodimentsdescribed above and can be modified in various manners without departingfrom the essence and gist of the present invention.

For example, the fluid pressure device may be configured to use workingoil as pilot fluid. The fluid pressure device may be a device other thana flow rate control valve, such as an actuator, etc.

Further, while in this embodiment, the fittings for connecting the pipemembers in which the fluid subjected to flow rate control flows includethe first nuts 40 and the second nuts 42, the fittings for connectingthe first supply/discharge pipe 144 and the second supply/discharge pipe146 to the first pilot port 86 and the second pilot port 102 may includethe first nuts 40 and the second nuts 42.

Further, the first pilot port 86 and the second pilot port 102 may bearranged in a row with the second joint body 50.

Furthermore, as shown in FIG. 16, an end plate 250 may be constructedwithout the first tab 28 and the second tab 30. In this case, threadedholes (not shown) are formed in the lower surface of the end plate 250and elongated holes (not shown) are formed through the base 12, andmounting screws (not shown) are inserted respectively into the elongatedholes and screwed in the threaded holes. In this case, the absence ofthe first tab 28 and the second tab 30 allows the first air-operatedvalve 14 a and the second air-operated valve 14 b, and the secondair-operated valve 14 b and the third air-operated valve 14 c, to belocated closer.

With this configuration, as shown in FIG. 17, when the fitting nuts 230of the conventional technique are used, a pitch P1′ between adjacentfitting nuts 230 can be set smaller than the pitch P1 in FIG. 8.However, in this case, too, it is necessary to ensure that the pitch P1′is not less than the sum of the outer diameter of the fitting nut 230(the outer diameter of the large-diameter tube portion 170) and the toolwidth of the second tool 210. Accordingly, it may be not possible tomost closely locate the first air-operated valve 14 a and the secondair-operated valve 14 b, and the second air-operated valve 14 b and thethird air-operated valve 14 c.

In contrast, as shown in FIG. 18, when the first nuts 40 (or the secondnuts 42) are used, relatively large clearance is formed between adjacentsmall-diameter tube portions 172. When turning the first nut 40 (or thesecond nut 42), the small semicircular ring 204 of the first tool 200can be inserted in the clearance and fitted around the small-diametertube portion 172 as explained earlier.

Accordingly, in this case, too, it is possible to set a pitch P2′between adjacent first nuts 40 (or adjacent second nuts 42) to besubstantially equivalent to the outer diameter of the large-diametertube portion 170. It is therefore possible to make the fluid controlsystem 10 compact by omitting the first tab 28 and the second tab 30 andmost closely locating the first air-operated valve 14 a and the secondair-operated valve 14 b, and the second air-operated valve 14 b and thethird air-operated valve 14 c.

Needless to say, in the configuration shown in FIG. 18, the first nut 40(or the second nut 42) can be easily tightened by engaging theengagement claws 206 of the first tool 200 with the engagement grooves186 formed around the small-diameter tube portion 172 of the first nut40 (or the second nut 42).

The first to third air-operated valves 14 a to 14 c may be constructedas normally-opened valves. In this case, the return spring 100 isprovided on the lower surface side of the piston portion 108 so as toresiliently bias the piston portion 108 toward the second housing 26.While the second supply/discharge pipe 146 is attached to the secondpilot port 102, the first pilot port 86 may be closed by a plug member.

Alternatively, the first to third air-operated valves 14 a to 14 c maybe constructed as so-called double-acting valves. In this case, thefirst to third air-operated valves 14 a to 14 c are brought into theopened state by supplying pilot fluid from the first pilot port 86 intothe upper chamber 82, while the first to third air-operated valves 14 ato 14 c are brought into the closed state by supplying pilot fluid intothe second housing 26 from the second pilot port 102. It is thereforenot particularly necessary to incorporate the return spring 100 in thisconfiguration.

What is claimed is:
 1. A fitting nut made of a resin material and havinga female thread that is engaged with a male thread formed on an outerperipheral wall of a joint body made of a resin material, the fittingnut comprising: a large-diameter tube portion that is hollow andincludes the female thread formed on an inner peripheral wall thereof;and a small-diameter tube portion that is continuous to thelarge-diameter tube portion, has a hollow cylindrical shape with asmaller diameter than the large-diameter tube portion and includes, inan end surface thereof, an insertion hole in which a pipe member isinserted, wherein the small-diameter tube portion includes a pluralityof engagement grooves formed in an outer peripheral wall thereof, theplurality of engagement grooves being depressed inwardly in a diameterdirection of the small-diameter tube portion and extending along alongitudinal direction that is orthogonal to the diameter direction. 2.The fitting nut according to claim 1, wherein the large-diameter tubeportion has a plurality of engagement protrusions formed on an outerperipheral wall thereof, the plurality of engagement protrusionsprotruding outwardly in a diameter direction of the large-diameter tubeportion and extending along a longitudinal direction that is orthogonalto the diameter direction.
 3. A fitting comprising: a fitting nut madeof a resin material and having a female thread formed thereon; and ajoint body made of a resin material and having, on an outer peripheralwall thereof, a male thread that is engaged with the female thread,wherein the fitting nut includes a large-diameter tube portion that ishollow and includes the female thread formed on an inner peripheral wallthereof, and a small-diameter tube portion that is continuous to thelarge-diameter tube portion, has a hollow cylindrical shape with asmaller diameter than the large-diameter tube portion and includes, inan end surface thereof, an insertion hole in which a pipe member isinserted, and the small-diameter tube portion includes a plurality ofengagement grooves formed in an outer peripheral wall thereof, theplurality of engagement grooves being depressed inwardly in a diameterdirection of the small-diameter tube portion and extending along alongitudinal direction that is orthogonal to the diameter direction. 4.The fitting according to claim 3, wherein the large-diameter tubeportion of the fitting nut includes a plurality of engagementprotrusions formed on an outer peripheral wall thereof, the plurality ofengagement protrusions protruding outwardly in a diameter direction ofthe large-diameter tube portion and extending along a longitudinaldirection that is orthogonal to the diameter direction.
 5. A fluidpressure device in which a fluid supply pipe configured to supply afluid, a fluid discharge pipe configured to discharge the fluid, and apilot fluid passage pipe configured to allow a pilot fluid to flowtherethrough, are connected respectively through fittings, wherein atleast one of the fittings includes a fitting nut made of a resinmaterial and having a female thread formed thereon, and a joint bodymade of a resin material and having, on an outer peripheral wallthereof, a male thread that is engaged with the female thread, thefitting nut includes a large-diameter tube portion that is hollow andincludes the female thread formed on an inner peripheral wall thereof,and a small-diameter tube portion that is continuous to thelarge-diameter tube portion, has a hollow cylindrical shape with asmaller diameter than the large-diameter tube portion and includes, inan end surface thereof, an insertion hole in which the fluid supplypipe, the fluid discharge pipe, or the pilot fluid passage pipe isinserted, and the small-diameter tube portion includes a plurality ofengagement grooves formed in an outer peripheral wall thereof, theplurality of engagement grooves being depressed inwardly in a diameterdirection of the small-diameter tube portion and extending along alongitudinal direction that is orthogonal to the diameter direction. 6.The fluid pressure device according to claim 5, wherein thelarge-diameter tube portion of the fitting nut includes a plurality ofengagement protrusions formed on an outer peripheral wall thereof, theplurality of engagement protrusions protruding outwardly in a diameterdirection of the large-diameter tube portion and extending along alongitudinal direction that is orthogonal to the diameter direction. 7.The fluid pressure device according to claim 5, wherein the fluid supplypipe or the fluid discharge pipe, and the pilot fluid passage pipe arearranged in a row.
 8. The fluid pressure device according to claim 5,further comprising a positioning and fixing member that is positionedand fixed on a certain member, wherein the positioning and fixing memberincludes, on point-symmetrical positions thereof, a first tab and asecond tab protruding in opposite directions and each having a throughhole formed along a thickness direction thereof.
 9. A fluid controlsystem comprising at least two fluid pressure devices that are arrangedadjacent to each other in a row, wherein, in each of the fluid pressuredevices, a fluid supply pipe configured to supply a fluid, a fluiddischarge pipe configured to discharge the fluid, and a pilot fluidpassage pipe configured to allow a pilot fluid to flow therethrough, areconnected respectively through fittings, at least one of the fittingsincludes a fitting nut made of a resin material and having a femalethread formed thereon, and a joint body made of a resin material andhaving, on an outer peripheral wall thereof, a male thread that isengaged with the female thread, the fitting nut includes alarge-diameter tube portion that is hollow and includes the femalethread formed on an inner peripheral wall thereof, and a small-diametertube portion that is continuous to the large-diameter tube portion, hasa hollow cylindrical shape with a smaller diameter than thelarge-diameter tube portion and includes, in an end surface thereof, aninsertion hole in which the fluid supply pipe, the fluid discharge pipe,or the pilot fluid passage pipe is inserted, and the small-diameter tubeportion includes a plurality of engagement grooves formed in an outerperipheral wall thereof, the plurality of engagement grooves beingdepressed inwardly in a diameter direction of the small-diameter tubeportion and extending along a longitudinal direction that is orthogonalto the diameter direction.
 10. The fluid control system according toclaim 9, wherein the large-diameter tube portion of each of the fittingnuts includes a plurality of engagement protrusions formed on an outerperipheral wall thereof, the plurality of engagement protrusionsprotruding outwardly in a diameter direction of the large-diameter tubeportion and extending along a longitudinal direction that is orthogonalto the diameter direction.
 11. The fluid control system according toclaim 9, wherein, in each of the fluid pressure devices, the fluidsupply pipe or the fluid discharge pipe, and the pilot fluid passagepipe are arranged in a row.
 12. The fluid control system according toclaim 9, wherein each of the fluid pressure devices further include apositioning and fixing member that is positioned and fixed on a certainmember, and the positioning and fixing member includes, onpoint-symmetrical positions thereof, a first tab and a second tabprotruding in opposite directions and each having a through hole formedalong a thickness direction thereof.
 13. The fluid control systemaccording to claim 9, wherein a pitch between the fitting nut of one ofthe fluid pressure devices and the fitting nut of another of the fluidpressure devices that is adjacent to the one fluid pressure device issubstantially equivalent to an outer diameter of a maximum outerdiameter portion of the fitting nuts.
 14. A nut turning tool for turninga nut, the nut turning tool comprising: an arc-shaped attachment portionshaped like an arc with an opening, the arc-shaped attachment portionbeing attached to the nut; and a shaft portion continuous to thearc-shaped attachment portion and extending linearly, wherein thearc-shaped attachment portion includes, on an inner surface thereof, oneor more claws protruding toward the nut, and the arc-shaped attachmentportion exhibits elasticity in a direction in which the opening isclosed after being expanded.
 15. The nut turning tool according to claim14, wherein the arc-shaped attachment portion is formed of a curvedplate.
 16. The nut turning tool according to claim 14, wherein the shaftportion has larger rigidity than the arc-shaped attachment portion. 17.A fitting nut turning method for turning a fitting nut using a nutturning tool to thereby engage the fitting nut with a joint body or torelease the engagement with the joint body, wherein the nut turning toolused includes an arc-shaped attachment portion shaped like an arc withan opening, the arc-shaped attachment portion being attached to thefitting nut, and a shaft portion continuous to the arc-shaped attachmentportion and extending linearly, the arc-shaped attachment portionincludes, on an inner surface thereof, one or more claws protrudingtoward the nut, and the arc-shaped attachment portion exhibitselasticity in a direction in which the opening is closed after beingexpanded, the fitting nut turning method comprising: causing the fittingnut to enter the opening while expanding the opening with the fittingnut; engaging the claw with an engagement groove formed in an outerperipheral wall of the fitting nut, while, when the entry of the fittingnut into the opening ends, closing the opening by the elasticity of thearc-shaped attachment portion to attach the arc-shaped attachmentportion to the fitting nut; and applying thereafter torque to thefitting nut through the shaft portion to turn the fitting nut.
 18. Thefitting nut turning method according to claim 17, wherein in a casewhere the fitting nut includes a large-diameter tube portion and asmall-diameter tube portion, the engagement groove is formed around thesmall-diameter tube portion, at least two fluid pressure devices eachincluding the fitting nut are located adjacent to each other and thefitting nuts thereof are placed adjacent to each other, and a pitchbetween the fitting nuts is substantially equivalent to an outerdiameter of the large-diameter tube portion, then the arc-shapedattachment portion is inserted from between the small-diameter tubeportions that are adjacent to each other.